The present invention relates to a vehicle towing device. More particularly, the invention is conveniently applicable to towing hooks for trucks and the like, for connecting a towing vehicle to a trailer.

The towing hooks commonly used on trailer trucks have a main body substantially shaped like a "C" and can be fixed to the rear of a tractor and having a latching housing arranged to receive a towing eye carried from the front by a trailer. The main body carries a protection cap at the top containing an actuation mechanism for vertically moving a latch pin between a closed position wherein it engages the latching housing defined by the "C" shape of the main body, and an open position wherein the housing is freely accessible to the eye through an access opening facing rearwardly with respect to the tractor.

The hook is fixed to a crossbeam carried at the rear by the tractor, by means of a cylindrical shank which protrudes from the main body on the opposite side and away from the access opening and extending through a crossbeam carried by the tractor. More particularly, the cylindrical shank is coaxially inserted through a collar carried by a fastening flange. A clamping nut engaged on a threaded end of the cylindrical shank determines the clamping of the collar between the main body and a thrust ring, after the interposition of elastomeric buffer rings.

Having to guarantee a high reliability in terms of road safety, towing hooks must meet strict safety criteria in terms of resistance and operating reliability, even when operating in rather severe environmental conditions. In this regard, the applicant observed some critical issues that may affect the reliability of use following prolonged use in the absence of rigorous checking. In particular, it has been observed that prolonged exposure to environmental agents tends to cause ageing of the elastomeric materials constituting the elastic rings arranged around the cylindrical shank. This ageing can cause breakages or anomalous wear phenomena of the rings, due to which the stability of the axial positioning of the hook with respect to the crossbeam is no longer guaranteed.

The prolonged exercise also tends to cause wear of the shank, of the collar, and/or of interposed annular bushes, generating undesirable mechanical backlash due to which there is no adequate retention of the hook with respect to the crossbeam. In particular, the hook can oscillate angularly in a more or less accentuated way with respect to the crossbeam, instead of maintaining a predetermined orthogonal orientation with respect to the crossbeam itself.

Another risk factor is represented by the possibility of a loosening of the clamping nut, for example following damage or loss of split pins or other retaining organs possibly associated with it.

The presence of these risk factors currently requires accurate periodic checking on the towing hooks whose execution, essentially entrusted to the user's good conduct, does not always occur with due care.

Moreover, even regardless the attention paid to the execution of the above described checking, it may happen that one or more mechanical components connecting the hook to the crossbeam are unexpectedly damaged or worn out during the vehicle travel, without any possibility for the driver to be aware of the upcoming dangerous situation.

The object of the present invention is to overcome the limits of the known art and improve the safety of use of the current towing hooks.

In particular, we want to offer a vehicle towing device that can promptly report any anomalies in the correct connection of the hook with respect to the crossbeam, caused by the possible breakage, wear or malfunctioning of one or more components.

A further object of the invention is to propose a technical solution which can also be applied to existing towing hooks, without requiring substantial structural modifications thereof.

These aims and others, which will become more apparent in the course of the following description, are achieved by a trailer vehicle towing device, according to claim 1.

In one embodiment, the towing device comprises: a coupling assembly removably engageable to a crossbeam carried at the rear by a vehicle; at least one sensor comprising a first portion rigidly engageable with respect to the crossbeam and a second portion rigidly carried by the coupling assembly, said sensor being switchable between a first and a second operating condition to signal operating anomalies in the connection of the coupling assembly with respect to the crossbeam, emitting a warning signal representing a relative anomalous displacement between the coupling assembly and the crossbeam following a relative displacement between the first portion and the second portion.

The invention may also have one or more of the preferential characteristics listed below.

The switching of the sensor from the first to the second operating condition takes place in response to a functional anomaly during the connection of the hook with respect to the crossbeam.

The warning signal emitted by the sensor is representative of a relative anomalous displacement between the coupling assembly and the crossbeam.

Preferably, it is also comprised a signaling device operatively connected to said sensor to emit an alarm signal in response to said warning signal. Preferably, said sensor comprises an inductive detector and a ferromagnetic insert respectively carried by one and the other of said first and second portions.

Preferably, the coupling assembly comprises a main body having a latching housing accessible from an access opening and configured to receive a towing eye, and a latch pin operating through the latching housing to retain the towing eye.

Preferably, the first portion can be fixed against one side of the crossbeam facing the main body, and the second portion of the sensor is fixed to the main body on the opposite side with respect to the access opening. Preferably, the first portion of the sensor comprises a shaped plate protruding from a support bracket rigidly engageable to the crossbeam. Preferably, the main body further comprises a protection cap which houses an actuation mechanism operating on the latch pin to move it axially through the latching housing.

Preferably, the second portion of the sensor is fixed to an external side of the protection cap.

Preferably, the second portion of the sensor is at least partially housed in a box-like protective structure removably fixed to the main body.

Preferably, the second portion of the sensor comprises an inductive detector.

Preferably, the inductive detector has its own end protruding through a bottom wall of the box-like protective structure.

Preferably, the end of the inductive detector faces at a short distance from a protruding tab of the shaped metal plate.

Preferably, the coupling assembly further comprises a cylindrical shank protruding from the main body, through the crossbeam, and a fastening flange rigidly engageable to the crossbeam and bearing a collar coaxially crossed by the cylindrical shank.

Preferably, the first portion of the sensor is engaged to the collar of the fastening flange, and the second portion of the sensor is formed on the cylindrical shank.

Preferably, the first portion of the sensor is engaged along a through hole obtained radially through a diametral shoulder of the collar.

Preferably, at least one grub screw engaged by screwing in a threaded hole formed in the diametral shoulder perpendicularly with respect to the through hole is provided, to block the first portion with its own free end at a desired distance from the external surface of the cylindrical shank.

Preferably, the first portion of the sensor comprises an inductive detector. Preferably, the second portion of the sensor comprises a surface discontinuity carried by the cylindrical shank, and radially facing the first portion of the sensor.

Preferably, the surface discontinuity is defined by a recess obtained on an external surface of the cylindrical shank.

Preferably, the cylindrical shank protrudes from the main body on the opposite side and away from the access opening.

Preferably, the coupling assembly further comprises a clamping nut engaged by screwing on a threaded end of the cylindrical shank, for clamping the main body against one end of the collar of the fastening flange.

Preferably, said diametral shoulder is configured to be axially interposed between the crossbeam and the clamping nut.

Preferably, the coupling assembly further comprises a first elastic ring circumscribing the cylindrical shank.

Preferably, the first elastic ring is axially interposed between the collar of the fastening flange and a thrust ring axially interposed between the collar itself and the clamping nut.

Preferably, the first elastic ring is housed in an annular groove formed on one side of the diametral shoulder facing the thrust ring.

Preferably, the coupling assembly further comprises a second elastic ring fitted around the cylindrical shank.

Preferably, the second elastic ring is axially interposed between the main body and the collar of the fastening flange.

Further characteristics and advantages will become more apparent from the detailed description of a towing hook preferably for trailer vehicles, according to the present invention.

This description will be set forth below with reference to the accompanying drawings, provided for purely illustrative and, therefore, non-limiting purposes, in which:

- figure 1 shows a towing device in a perspective view according to the present invention: - figure 2 shows the towing device in a perspective view from the opposite side with respect to figure 1 ;

- figure 3 shows the perspective view of figure 2 sectioned longitudinally;

- figure 4 is a longitudinal section of the towing device.

With reference to the aforementioned figures, the numeral 1 globally indicates a vehicle towing device, according to the present invention.

The device 1 comprises a coupling assembly 2 removably engageable to a crossbeam 3 carried at the rear by a vehicle, for example a tractor (not shown). In the illustrated example, the crossbeam 3 is defined by a metal profile having a substantially C-shaped section, with two terminal appendices 3a facing the tractor, from the opposite side with respect to the coupling assembly 2.

Preferably, the coupling assembly 2 comprises a main body 4 having a latching housing 5 accessible from an access opening 6 facing rearwardly with respect to the tractor carrying the crossbeam 3. The latching housing 5 is configured to accommodate a ring terminal, usually called "eye", carried by a towing bar associated with a trailer (not shown). The eye is not shown since it is known and can be inserted and removed through the access opening 6. A guide element 7, usually referred to as "drawbar coupling", facilitates the entry of the eye into the latching housing 5 during the latching operation.

In a per se known manner, a latch pin 8 operates through the latching housing 5 to retain the towing eye.

Preferably, the latch pin 8 is slidably guided through the main body 4 and movable longitudinally along a respective working axis Y, between a closed position in which it engages the latching housing 5, and an open position in which it releases the access to the latching housing itself, to allow engagement and disengagement of the eye and, therefore, of the trailer. The axial movement of the latch pin 8 through the latching housing 5 can be controlled by an actuation mechanism 9, not described in detail since it is known, housed inside a protection cap 10 presented by the main body 4. More particularly, the protection cap 10 is preferably solidly connected to the upper part of the main body 4.

The coupling assembly 2 is coupled with the crossbeam 3 preferably by means of a cylindrical shank 1 1 which protrudes from the main body 4 from the opposite side of the access opening 6 and cooperates with a fastening flange 12 solidly connected to the crossbeam 3.

Preferably the fastening flange 12 is rigidly engaged to the crossbeam 3, for example by means of bolts 13 or other threaded members, and carries a collar 14 which extends through a through opening 15 provided in the crossbeam 3 itself. The collar 14 is coaxially crossed by the cylindrical shank 1 1 , which therefore extends through the crossbeam 3 away from the access opening 6, until it protrudes from the collar itself with its own threaded end 16.

One or more wear bushes 17 can be operatively interposed between the inner surface of the collar 14 and the external surface of the cylindrical shank 1 1.

On the threaded end 16 a clamping nut 18 is engaged by screwing, configured for clamping the main body 4 against a first end 14a of the collar 14 of the fastening flange 12. A safety split pin 16a prevents unwanted loosening of the clamping nut 18.

The clamping nut 18 operates against a thrust ring 19 axially interposed between the clamping nut 18 itself and a diametral shoulder 20 arranged near a second end 14b of the collar 14. Preferably the diametral shoulder 20 is formed integrally with the collar 14, and is axially interposed between the crossbeam 3, against which it acts directly in contact, and the clamping nut 18, after interposition of the thrust ring 19 and a first elastic ring 21. The first elastic ring 21 can be conveniently housed in an annular groove 22 formed on one side of the diametral shoulder 20 facing the thrust ring 19, away from the crossbeam 3. The first elastic ring 21 therefore circumscribes the cylindrical shank 1 1 , and is axially interposed between the collar 14 of the fastening flange 12 and the thrust ring 19.

A second elastic ring 23 is preferably fitted around the cylindrical shank 11 , and axially interposed between the main body 4 and the collar 14 of the fastening flange 12, on the opposite side with respect to the clamping nut 18.

On the first end 14a of the collar 14 a thrust disc 24 can also be provided, arranged to act against the second elastic ring 23 to compress it against the main body 4.

The towing device 1 is conveniently associated with at least one sensor S1 , S2 configured to detect relative anomalous displacements between the main body 4 of the coupling assembly 2 and the crossbeam 3.

In the illustrated example, the towing device 1 is equipped with a first sensor S1 and a second sensor S2, each of which comprises a first portion P1 rigidly engageable with respect to the crossbeam 3 and a second portion P2 rigidly carried by the coupling assembly 2.

In one preferred embodiment, each sensor S1 , S2 essentially comprises an inductive detector 25 and a ferromagnetic insert 26 respectively carried by one and the other of said first and second portions P1 , P2.

Various alternatives can be chosen instead of using inductive detectors, such as for example capacitive, magnetic, optical, ultrasonic detectors or even mechanical microswitches.

In the first sensor S1 , the ferromagnetic insert 26 and the inductive detector 25 make part respectively of the first and the second portion P2. On the contrary, in the second sensor S2, the first and second portions P1 , P2 comprise the inductive detector 25 and the ferromagnetic insert 26, respectively.

The first portion P1 of the first sensor S1 is fixed against a side of the crossbeam 3 facing the main body 4. The ferromagnetic insert 26 can be constituted by a shaped metal plate, protruding from a support bracket 27 rigidly engaged to the crossbeam 3. More particularly, the engagement of the support bracket 27 can be conveniently obtained by the same bolts 13 used to fasten the fastening flange 12.

The second portion P2 of the first sensor S1 is in turn fixed to the main body 4. The inductive detector 25 of the first sensor S1 , being an integral part of the second portion P2, can be at least partially housed in a box-like protective structure 28, removably fixed on an external side of the protection cap 10, on the opposite side with respect to the access opening 6. A free end 25a of the inductive detector 25 protrudes through a bottom wall of the box-like protective structure 28, and faces a short distance from a projecting tab 26a of the shaped metal plate 26.

With reference to the second sensor S2, the first portion P1 essentially consists of the respective inductive detector 25 and is engaged in a through hole radially made through the diametral shoulder 20 of the collar 14. A grub screw 30 and a possible counter grub screw 30a are engaged by screwing into a threaded hole made in the diametral shoulder 20 perpendicularly with respect to the through hole 29, to lock the inductive detector 25 with its free end 25a at a desired distance from the external surface of the cylindrical shank 1 1. The ferromagnetic insert 26 forming part of the second portion P2 of the second sensor S2 can in turn be obtained directly in the cylindrical shank 1 1 , by means of its surface discontinuity radially facing the first portion P1 of the sensor S1 , S2. For example, this surface discontinuity can be defined by a recess 32 of adequate depth, formed in the external surface of the cylindrical shank 1 1. It should be noted that the presence of both the first and second sensor S1 , S2 is not necessary, since only one of them can be sufficient to meet the requirements. In general, the use of the embodiment described with reference to the first sensor S1 is particularly suitable for the installation on already existing towing hooks, without requiring particular processing. The first and second portions P2 of the first sensor S1 are suitable in fact to be directly applied on external parts of the coupling assembly 2 and of the crossbeam 3. The embodiment represented by the second sensor S2 is in turn more suitable to be used on newly produced coupling assembly, equipped for this purpose with the recess 32 on the cylindrical shank 1 1 and the through hole 29 in the shoulder 20 of the collar 14 for the housing of the inductive detector 25, which is particularly protected against external environmental agents.

In both embodiments, during the normal operating conditions of the coupling device 1 , the inductive detector 25 and the respective ferromagnetic insert 26 remain aligned according to a substantially stable positioning, which can be modified possibly only after slight and admissible oscillations of the coupling assembly 2 around the axis of the cylindrical shank 1 1 , typically due, for example, to shakings and relative movements which occur between the tractor and the trailer while driving. These displacements are within the limits of acceptability and do not cause significant reciprocal displacements between the inductive detector 25 and the respective ferromagnetic insert 26.

Advantageously, any breakage, wear, or other malfunctioning of one of the components of the coupling assembly 2 causes a relative displacement between the first portion P1 and the second portion P2 of the sensor S1 , S2, and a consequent variation of the magnetic field in proximity of the free end 25a of the inductive detector 25. More specifically, a significant field variation may occur for example in the presence of at least one of the following circumstances:

- breakage and/or mechanical or ageing wear of one or both of the elastic buffer rings 21 , 23, and consequent misalignment of the ferromagnetic insert 26 with respect to the inductive detector 25 due to the axial sliding of the cylindrical shank 1 1 inside the collar 14;

- loosening of the clamping nut 18, for example following the breakage or loss of the safety split pin 16a or other retaining member, and consequent misalignment of the ferromagnetic insert 26 with respect to the inductive detector 25, due to the axial sliding of the cylindrical shank 1 1 inside the collar 14;

- consumption of wear bushes 17 and consequent misalignment of the ferromagnetic insert 26 with respect to the inductive detector 25 due to the transverse oscillation of the cylindrical shank 11 inside the collar 14;

- anomalous inclination of the trailer with respect to the tractor, with consequent misalignment of the ferromagnetic insert 26 with respect to the inductive detector 25 due to the rotation of the cylindrical shank 11 around its own axis X inside the collar 14 beyond a predetermined limit.

At least in any of the circumstances described above, the inductive detector 25 therefore lends itself to detecting the field variation and consequently switches its state from a first operating condition, corresponding to the state of normal operation of the towing device 1 , to a second operating condition, corresponding to the output of a warning signal.

The sensor S1 , S2 can be conveniently connected to, by means of a connection line L1 , L2 by cable or in wireless mode, a signaling device, for example of the optical or acoustic type, installed for example in the driving cab of the tractor, to immediately notify the driver of the unexpected functional anomaly of the towing device 1.

The safety of use of the towing device is thus increased, since the driver of the vehicle is constantly informed in real time on the state of correct or anomalous operation of the towing device 1.